David b



DAVID Bf. MARKS; on New Yoan; Y. A

ARTIFI-.GIAL LEG.;

Specification of Letters Patent No.. 10,611, .dated March 7, 1.85.4.

To all Iwhom/15 may 00m/era:

Be it known that I, DAVID. B. MARKS, of

the city, county, and State of New: York,

have invented a new and useful Improvement in Artificial Legs; and I do herebyv declare that the following is a full, clear, and exact description of thev same., reference being made to the accompanying drawings,

L:making a vpart of this specification, in

Figure l, shows the limb and foot, in section, in two ofthe positions of walking; one of the positions being shown in black,and the other in red color. Fig.. 2, shows the same, bent as when the wearer lis in a sitting posture. FigB, is a side view of the curvedl bar, by which the movement of the, knee" joint is controlledwith a section of the head of the rod and roller which are connected with the foot. Fig. 4, is a front view of the same.

Similar letters of reference indicate cor responding parts in each of the several figures.

This limb is intended to perform, in walking, all the movements of the natural limb. In taking a step, the foot is brought flat to the ground, with a perfect rigidity of the knee joint, which is maintained until the ankle is bent by the throwing forward of the body as the opposite leg takes the succeeding step.I This bending of the ankle leaves the knee free to make the slight bend which is necessary to raise the heel from tlhe ground; and when the knee is thus bent, the ankle becomes stiff, with the toe raised to prevent its dragging during the early'portion of the movement of the leg in taking the next step; and it remains sti until it is necessary, for the straightening of the lmee and the throwing down of the toe, to bring the foot flat to the ground, both of which latter movements are effected simultaneously. y

My invention relates to the means by which the movements of the knee and ankle joints are controlled, and the necessary rigidity is maintained during the cessations in those movements.

To enable those skilled in the art to make and use my invention, I will proceed to describe its construction and operation.

A, B, and C, (Figs. 1, and 2,) represent the thigh, leg, and foot, which may be made of any known material, of sufficient strength to support the weight of the body. The leg is connected` with the thigh and with the foot,l by hinge joints, a, b., ball and socket joints, or any kother connection most suitable to representy the knee and ankle joints;v

the. thigh piece, A, and legv piece, B, beingv provid-ed `with stops, f, j, which comeincontact when the knee is straight, and thus preventy its being thrown too far back. The thigh and leg may be made hollow', or the v latter must have suicieni'.l space within it, for the passage ofA a rod, D, which isfconnected at its lower end with the foot, in front ofthe ankle joint b, and which works;

' through a guideor guides c, e, under one of which, or attached' in-somefsuitable wayv to the leg, B, or spring, d, coils round the rod,

`to whichv it is firmly secured. rIhe effect of this springA is to throw down the toe or front end ofthe, foot. The upper end ofthe rod is furnished with a roller, e, which works..

in'contact with the :face: of a curvedy bar, E, which is rigidly attached to the thigh at the back of the knee joint, a. The curved bar proceeds from its place of attachment, for some distance in a straight line, then formsva hollow curve, g, on its face, next a smaller rounded curve, k, then for a very short distance is nearly straight, and the terminating portion forms a small arc, (i), which fits to the periphery of the roller at the top of the rod, D.

In bending the knee, the curved bar, E,

works under the roller, e; but when the leg isstraightened, as shown in Fig. 1, in black, which figure represents the foot thrown forward and placedon the ground, as when the step is made; the terminating curve, z', of the curved bar, fits to the back and under parts of the roller. The back of the roller com-ing in contact with the bar, prevents thepossi- Y bility of bending the knee without raising the roller, e, and rod, D, and holds the stops,

7, in contact, making the knee perfectly stiff.--

The extremity `of the bar, E, holds 'ufp the roller, e, against the tension of the spring, d, and'while it allows the front of the foot to bend upward from the ankle with a mod When the upper part of the..

ceeding step with the opposite foot,-the .y

limb is shown in red color in Fig. 1, making' Q y this movement,-the ankle is the first joint in which any movement is made; andthe bend which there takes place, moves the rod,

D, andits roller, e. upward fromfthe posi-V tion where ythey hold the knee sti. As the and the rod' further raised, and there is a tendency to bend at the knee; this tendency is allowed to operate; and the roller, e, moves up the rounded curve, 7L, of the curved bar, until it reaches a position where it will rest, which willlbe about the position indicated by dotted circles in the red portion of Fig. 1. By stopping'in that position, the

: roller and rod keep the toe raised, and the knee slightly bent, during the early port-ion of t-he next step; but as the foot reaches the end of its forward movement, the lower part of the limb acquired such momentum that, when the forwardmovement from the thighv ceases, the knee is straightened by its continued motion; and the roller, e, descending the curve, It, throws down the toe, and arrives at the hollowcurve, z', where it againv locks the knee stiff, with the foot in position to be brought flat, or nearly so, upon the ground.` p y To bend the knee for sitting down', the weight requires t'o be thrown upon the'front of the foot, and the ankle bent enough to raise the roller, e, high enoughvto `run over the rounded curve, h, when nopfurther ob- Vbut that of the spring,

stacle t0 the bending is encountered, runtil it is bent as far as necessary, when the back stops, j, j, of the leg and thigh, meet; the roller following" the hollow curve, g, and thereby descending far enough to allow the foot to come down flat. .No obstacle is offered to the straightenin of the leg again, during the early part of the movement, which will be easily 'overcome by placing the foot `flat, on the ground, and raising the body.

What I claim as my invention, `and desire I to secure by ,Letters-Patent, is-

The combination of the rod, D, which is attached to the foot, and movesA upward and downward, within the leg or lower part of the limb, the spring, d, applied to the rod, andthe curved bar, plate, or way, E, at-` tached to the thigh or upper part of the limb, the whole operating substantially as described, to lock .the knee stift1 and control the position Vof the foot, until the ankle is bent on'ythrowingfthe-body forward, and retain the foot in its' bent position at the ankle, until 'the knee `is again straightened, as herein fully `set forth. n

' y DAVID B. MARKS.` Witnesses; y i i Y WILLIAM STRONG, CHARLES WRIGHT. 

